1980 SG carbs on 1978 E

[SIZZSAM]

My brother asked me to tune up his bike and it's a 78 standard. I have a 78 standard also and when I was taking the carbs off I noticed that the air box didn't have the two vacuum hoses connected like mine. When I started taking the carbs apart they had 110 main jets like a 80 sg but the needle is like an 80 G going by the manual. Does anyone know of any particular problems with running the special carbs on the standard. The bike has four into one exhaust but the stock air box. Any help would be appreciated. Sam

[petejw]

Theres no problems in using carbs
from different years, they all work.
Just jet according to model of the carbs and not the model of the engine.

[SIZZSAM]

80 sg carbs on 78 standard

Thanks Pete for the help. Would you happen to know if the Mikuni jetting guide is posted somewhere on this site? I have an 80 special I bought that had four into one exhaust and pod filters and wanted to know if I needed to install larger main jets. If I roll on slow it will run smooth but if I twist it wao it spits a little. I think I saw a mikuni guide for sell on some bike site like Bike Bandit. If anyone knows from experience about changing exhaust and adding pods please let me know what they found... Thank you. Sam

[tarzan]

There is a whole thread about the jetting.I havent been there in a while but I think it is tech tips.Just do a search for jetting or jets .

[petejw]

Heres a link to the factory pro site that many of
us have used as a guide.

http://www.factorypro.com/tech_tunin...m_engines.html

Probably wouldnt hurt to check ur float heights if its playing up under throttle.


Heres a link to the jetting recomendations,

http://www.xs11.com/forum/showthread...=&threadid=382

[SIZZSAM]

80 sg carbs on 78 standard

Thanks Pete and Tarzen for the help. I'll go over the guide. The 80 Sg air box has the two vacuum ports plugged but the 78 E uses them. Since my brother has the 80 sg carbs on his 78 E and has the stock 78E airbox do you think I should plug the two vacuum ports on the airbox or will it matter? Thank you again for your replies. Sam

[randy]

I would plug them or they'll draw a small amount of unfiltered air.

[SIZZSAM]

80 sg carbs on 78 standard

Thank you Randy for your reply. After I clean them up a little I think everything should run just fine. I should have them back together sometime tomorrow. I appreciate all the help...Sam